1. Field of the Invention
The present invention relates to a bearing apparatus for an axle of a vehicle of an automobile, a truck or the like, further in details, relates to a bearing apparatus for an axle including a seal member of preventing muddy water from invading an inner side of a bearing portion.
2. Related Art
A bearing portion of a bearing apparatus for an axle of a background art is constituted by an inner ring, an outer ring, a roller and a retainer.
The bearing portion includes a seal member for sealing an opening portion of an outer side and an inner side constituting end portions in an axial direction of an inner ring and an outer ring of the bearing portion.
The seal member is constituted by including a core having a section in an L-like shape fixed to an inner peripheral face of the end portion in the axial direction of the outer ring, an elastic member fixedly attached to the core, and a slinger having a section in an L-like shape fixed to an outer peripheral face of the end portion in the axial direction of the inner ring.
Further, the elastic member includes three lips at a front end thereof and the lips are brought into close contact with the slinger.
The seal member seals an inner space of the bearing portion against an outer space of the bearing portion by bringing the lips of the elastic member fixedly attached to the core into close contact with the slinger.
Further, the seal member prevents muddy water or the like from invading an inner side of the seal member per se from an outer portion thereof by arranging the slinger such that a gap between a diameter direction portion of the slinger and an axial direction portion of the core (labyrinth) becomes as small as possible. (Refer to, for example, JP-A-7-186604).
Although flow-out of a lubricant and invasion of muddy water are prevented by mounting the seal member to the opening portion on the inner side and the outer side of the inner ring and the outer ring in the background art in this way, there is a case in which a seal performance is insufficient only thereby, and therefore, various measures are taken on the inner side at which invasion of muddy water is particularly significant to achieve an effect.
Although a sufficient sealing property can be maintained in useful life requested for a general passenger vehicle, when maintenance-free of an extremely long period of time requested for a large-sized truck is used, a probability by which muddy water or the like invades the inner portion from the gap of the seal portion becomes high.
Further, when as a result of the invasion of the muddy water, the muddy water or the like is made to percolate in an interval between the lip of the elastic member and the slinger, the seal property of the lip is deteriorated, muddy water or the like invading the inner portion of the seal member passes through the lip of the elastic member, passes through even the gap between the diameter direction portion of the core and the slinger, and it is conceivable that the life of the bearing portion is reduced owing to the invasion of water from the seal portion.